"Optimal" tire pressure

C

CuriousGeorge

Well-Known Member
(Quotes because it depends on what parameter you wish to optimize.)

On another forum @SameGuy was kind enough to answer my question about his preferred tire pressures (40/37 with F1s). Since the Goodyears on the loaner I have at present were underinflated, I decided to do the dealership a favor and pumped them up to the above. Overall, I would say that experiment was a success, with a bit sharper response to steering input but only a slight decrease in ride quality (mostly more vibration on coarse surfaces). Interestingly, the higher pressure seemed to help straight line traction, as flooring the accelerator immediately pegged the power delivery to 100%, with no complaint from the tires and without setting off the traction control. In contrast, when the front tires were at 33-34 psi, initial power delivery was restricted, the traction control would kick in, and the tires would squeal. Since my spouse doesn't like being thrown around, I didn't get the chance to explore the cornering limits, and obviously can't really say anything about the effects on range or wear pattern (although I should be able to gather some data re. the first two tomorrow).

Anyway, I am now motivated to play with higher pressures for the P7s when I get my own car back. Anybody else tried pressures higher (or lower) than factory recommended for daily use? If so, what was your experience?
 
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One thing I found in the other place is that the door jamb tire pressure label is different in the UK, showing different choices for riding 2-up, 2-up "ECO," and 4-up. 2-up is too soft for me, while "ECO" is harder than I'm comfortable riding on our terrible roads, and I'm pretty sure would make uneven wear a fairly important consideration.

upload_2024-9-16_0-0-38.webp
 
SameGuy said:
One thing I found in the other place is that the door jamb tire pressure label is different in the UK, showing different choices for riding 2-up, 2-up "ECO," and 4-up. 2-up is too soft for me, while "ECO" is harder than I'm comfortable riding on our terrible roads, and I'm pretty sure would make uneven wear a fairly important consideration.

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Thanks, you'd mentioned the difference, but it's helpful (or at least more memorable for me) to see it laid out on the label/in a table.

So, next time one plans a longer trip outside the urban minefield of potholes, raise the pressure to extend range, then drop it back down to, e.g., ferry around the inlaws?

A bit more seriously: I may be making a "4 up" trip out of town later this month. Looks like I should definitely raise the pressure a couple/few psi
 
Yeah the standard for our labels here is "at maximum load," whatever that might be for individual vehicles. I think "39/35" for the UK max load is within the margin of error of most gauges and TPMS sensors compared to our label's "38/35." It may even be a rounding error from bar to psi.
 
I asked my service manager about this, and he said I should follow the label on my Mini (take his advice with a grain of salt).
 
Upper 80s here today (temp gauge in the car was showing 35°C – 95°F!), BOY were my 40/37 tires squealing loudly on the same left-right that made my fortwo wag its tail for 50 yards. Gonna bring the rears up to 40 and try again.:cool:
 
SameGuy said:
Upper 80s here today (temp gauge in the car was showing 35°C – 95°F!), BOY were my 40/37 tires squealing loudly on the same left-right that made my fortwo wag its tail for 50 yards. Gonna bring the rears up to 40 and try again.:cool:
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Unfortunately, I still haven't had a chance to push the loaner through any turns at speed - too many other cars/construction getting in the way. Probably not tomorrow either, but hopefully I will get my own car back in the afternoon and can start experimenting with different pressures in the P7s.
 
We have two SEs in the household. The 22 came with the F1s, the 23 with P7s. I drive the 23 and just switched the P7s to F1s after 17k miles. Every time I would get in the 22, I would immediately notice the difference(smoother, sharper etc). I find the ride to be smoother at the door jamb label pressures. Anything below that seems to make the steering/ride sloppy. Do you set pressures using the car tpms readings or tire gauge only? I set mine using a digital Moroso gauge and the in car readings are usually reading 1-2 psi below what gauge says.
 
bmartinez028 said:
We have two SEs in the household. The 22 came with the F1s, the 23 with P7s. I drive the 23 and just switched the P7s to F1s after 17k miles. Every time I would get in the 22, I would immediately notice the difference(smoother, sharper etc). I find the ride to be smoother at the door jamb label pressures. Anything below that seems to make the steering/ride sloppy. Do you set pressures using the car tpms readings or tire gauge only? I set mine using a digital Moroso gauge and the in car readings are usually reading 1-2 psi below what gauge says.
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Interesting comparison. Unfortunately, I won't be able to drive the loaner and my car back-to-back at the same pressure.

My tire gauge, pump, and both SEs all agree to w/in 0.5 psi.
 
Nobody here mentioned a tire sizes as my 2022 is on 195/55/16 Hankooks my door label recommended tire pressure is 35 PSI /32 PSI which I see the car best response with that setting.As I’m inflate my tire at Costco always putting 2 PSI higher and as I’m resetting tire pressure in a car I’m getting perfect 35/32 PSI .For 17” or 18” will be different pressure recommendations
 
Rexsio said:
Nobody here mentioned a tire sizes as my 2022 is on 195/55/16 Hankooks my door label recommended tire pressure is 35 PSI /32 PSI
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The UK label that @SameGuy posted has tire sizes. Curiously for both the 16" and 17" standard sizes it recommends the same pressure. I didn't even know the SE came with these size tires:

175/60 R 16 86 H XL M+S
185/50 R 17 86 H XL M+S​
 
CuriousGeorge said:
I won't be able to drive the loaner and my car back-to-back at the same pressure.
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I pumped my P7s up to 40/37 today, and if anything I would actually say that they are more responsive and smoother than the F1s at the same pressure (they are definitely quieter). But, unlike @bmartinez028, I didn't get to repeatedly compare them.

Either way, I'm sticking with the higher pressure for now. The roads I normally drive are pretty smooth, so comfort really isn't a consideration - I'm after handling first and foremost, with range a distant second.
 
CuriousGeorge said:
I pumped my P7s up to 40/37 today, and if anything I would actually say that they are more responsive and smoother than the F1s at the same pressure (they are definitely quieter). But, unlike @bmartinez028, I didn't get to repeatedly compare them.

Either way, I'm sticking with the higher pressure for now. The roads I normally drive are pretty smooth, so comfort really isn't a consideration - I'm after handling first and foremost, with range a distant second.
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If you are with 40/37 PSI you are 5 PSI above factory recommendation just read this and with directly temperature affects tire pressure for every 10 degrees increase temperature your air pressure will increase by 1 PSI as you are driving in 100’F. Weather your tires will be at 43/40 PSI which is just dangerous and high way speed of 70 M/Hr.increase PSI higher.As I keep my 16” Hankooks at 35/32 PSI as many people complain about wearing mine as new with 16000 miles IMG_1681.webp
 
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